Motor will not start, if I spin the blades it will run

Before you start removing covers and panels unplug the mower. Turn the mower over and carefully try to spin the blade by hand. Your checking to where the issue is most likely to be.
Does the motor sound different when you pull the Start trigger? If it sounds a lot faster than normal, it could be an issue between the motor and gearbox.
Does the blade spin really easily and feel like it's not bolted down? Does the blade not turn at all like it's 'locked' or 'jammed'?
- A loose or floppy blade is commonly the centre mount bolt for the blade is loose or the blade isn't seated correctly.
- A 'locked' blade could be a gearbox or a motor issue.

SOLVED: Why won't my blades turn? - Oster Blend-N-Go My Blend - iFixit

https://www.ifixit.com/Answers/View/259808/Why+won't+my+blades+turn

3 answers
Oct 1, 2015 - The blades may not be turning because the blade assembly is not fully ... Blades do not turn but the motor runs. ... this is a touch and go motor so it is easy to start the motor withoutproperly ... The blade should turn, if not they need to be replaced. ... My blender isn't even a year old and blades wouldn't turn. Why is my Magic Bullet just humming, but the blades ...
1 answer
Oct 29, 2015
Why are the blender blades not rotating? - Ninja NJ600
6 answers
Apr 30, 2015
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call in an electrician as it may be the start/run capacitor for the motor ( indicated by motor humming but not running)
the gearing will make it very difficult to turn the blades by hand as the motor will be spinning at either 1400 rpms or 2400 rpms down to around 50 rpms for the blades

As stated earlier it could be the shaft needs lubing, remove the bottom part of the blender blade... the rubber thing that engages on the motor. I started with WD-40 and worked some lithium grease into it. Spins like new now.

Outdoor condensing fan motor has stopped running. This problem could be caused by a bad motor run capacitor. If your motor capacitor is not the problem, then more than likely you need a new motor. Is the fan blade tight, stiff or hard to turn? If the fan blade is hard to turn then you probably need a new motor

I'm guessing the condensor fan motor is not running. they smell like an electrical odor when they stop..remove back cover and see if something has gone into the blade area and stopped the motor from turning. if so, remove it ..if not, spin the blade and see if motor starts..if so, order new motor..you can use a floor fan to blow air towards compressor until you get a motor
Bruce

Maybe the bolt which holds the blade on is loose. If the motor is on the RIGHT side of the blade, then the bolt has 'left-hand' thread. Turn it counter-clockwise to tighten.

Be careful.....! If it starts when you push it you can hurt yourself seriously from the spinning blade. Sounds like your motor has a bad capaictor. Turn off the power (circiut breaker). Remove the old capaictor. Find the rating on the side. Replace it with the same rated size. If the motor has been subjected to running without a good capacitor for a while you "might" also need to replace the motor.
Good luck........

you have a loose nut.  Let me explain...the nut and washer that holds the blade to the motor has worked loose.  You need to remove the plate around the blade to acess it and on the end of the blade is a large nut.  Tighten it with the power off.  Sometime there is a grove on the motor shaft to hold the motor or sometimes you need to put a screwdriver into the teeth of the blade to hold in place to tighten. 

The pump out motor in line with the outlet pipe could be faulty. Remove the moto and connect it to the mains for a few seconds. The motor should spin and the impeler inside the motor should spin freely. If the motor is faulty it would not work and must be replaced